Samsung S3F80JB - Manual (Page 270)

TIMER 2 S3F80JB
13-2
TIMER 2 OVERFLOW INTERRUPT
Timer 2 can be programmed to generate an overflow interrupt (IRQ3, F0H) whenever an overflow occurs in the
16-bit up counter. When you set the timer 2 overflow interrupt enable bit, T2CON.2, to “1”, the overflow interrupt is
generated each time the 16-bit up counter reaches ‘FFFFH’. After the interrupt request is generated, the counter
value is automatically cleared to ‘00H’ and up counting resumes. By writing a “1” to T2CON.3, you can clear/reset
the 16-bit counter value at any time during program operation.
TIMER 2 CAPTURE INTERRUPT
Timer 2 can be used to generate a capture interrupt (IRQ3, vector F2H) whenever a triggering condition is
detected at the P3.0 pin for 32 pin package and P3.3 pin for 44 pin package. The T2CON.5 and T2CON.4 bit-pair
setting is used to select the trigger condition for capture mode operation: rising edges, falling edges, or both
signal edges.
In capture mode, program software can poll the timer 2 match/capture interrupt pending bit, T2CON.0, to detect
when a timer 2 capture interrupt pending condition exists (T2CON.0 = “1”). When the interrupt request is
acknowledged by the CPU and the service routine starts, the interrupt service routine for vector F2H must clear
the interrupt pending condition by writing a “0” to T2CON.0.
Interrupt
Enable/Disable
(T2CON.1)
IRQ3 (T2INT)
P3.0 or P3.3
(note)
Timer 2 Data
IRQ3 (T2OVF)
16-Bit Up Counter
CLK
T2CON.5
T2CON.4
Pending
(T2CON.0)
T2CON.2
NOTE: P3.0 is assigned as T2CAP function for 32 pin package and P3.3 is assigned
as T2CAP function for 42/44 pin package.
Figure 13-1. Simplified Timer 2 Function Diagram: Capture Mode